Commit 6aa159ba authored by jp7g21's avatar jp7g21
Browse files

Command reading code

parent 3a87c5ef
#include <stdio.h>
#include <stdlib.h>
#include "command.h"
#define NUM_COMMANDS 20
/* Cyclic buffer; when comm_start == comm_end, length = 0 */
struct command command_buf[NUM_COMMANDS];
uint16_t comm_start = 0, comm_end = 0;
/* Add y to x, wrapping around limit */
static inline void add_wrap(uint16_t *x, uint16_t y, uint16_t limit)
{
*x += y;
if (*x >= limit) *x %= limit;
while (*x < 0) *x += limit;
}
enum state {
STATE_COMM, STATE_COMM_SPACE, STATE_ARG
};
/* Return 1 if new command ready */
uint8_t uart_add_ch(char c)
{
static enum state state = STATE_COMM;
static char argbuf[20]; /* Buffer for storing argument */
static int argbuf_ind = 0; /* Index into argbuf of next character */
static int argnum = 0;
struct command *curr = &command_buf[comm_end];
switch (state) {
case STATE_COMM:
curr->comm_ch = c;
state = STATE_COMM_SPACE;
break;
case STATE_COMM_SPACE:
if (c == ' ') {
state = STATE_ARG;
} else {
state = STATE_COMM;
add_wrap(&comm_end, 1, NUM_COMMANDS);
}
break;
case STATE_ARG:
if (c == ' ' || c == '\n') {
argbuf[argbuf_ind] = '\0'; /* Terminate string */
curr->arg[argnum] = atoi(argbuf);
argbuf_ind = 0;
if (c == ' ') { /* More arguments follow */
argnum++;
} else { /* End of line */
argnum = 0;
state = STATE_COMM;
add_wrap(&comm_end, 1, NUM_COMMANDS);
}
} else {
if (argbuf_ind < 19) argbuf[argbuf_ind++] = c;
}
break;
}
return state == STATE_COMM;
}
struct command *get_command(void)
{
if (comm_start != comm_end) {
struct command *ret = &command_buf[comm_start];
add_wrap(&comm_start, 1, NUM_COMMANDS);
return ret;
} else {
return NULL;
}
}
#ifndef _COMMAND_H
#define _COMMAND_H
#include <stdint.h>
struct command {
char comm_ch; /* Character of command (ie 's', 'v', 'd') */
int16_t arg[2];
};
uint8_t uart_add_ch(char c);
struct command *get_command(void);
#endif /* _COMMAND_H */
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